CVE-2026-53080
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_fw: fix NULL dereference of "old" filters before change() Like pointed out by Sashik…
Published Jun 24, 2026 · updated Oct 15, 2026 · linux linux kernel
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_fw: fix NULL dereference of "old" filters before change() Like pointed out by Sashiko [1], since commit ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") TC filters are added to a shared block and published to datapath before their ->change() function is called. This is a problem for cls_fw: an invalid filter created with the "old" method can still classify some packets before it is destroyed by the validation logic added by Xiang. Therefore, insisting with repeated runs of the following script: # ip link add dev crash0 type dummy # ip link set dev crash0 up # mausezahn crash0 -c 100000 -P 10 \ > -A 4.3.2.1 -B 1.2.3.4 -t udp "dp=1234" -q & # sleep 1 # tc qdisc add dev crash0 egress_block 1 clsact # tc filter add block 1 protocol ip prio 1 matchall \ > action skbedit mark 65536 continue # tc filter add block 1 protocol ip prio 2 fw # ip link del dev crash0 can still make fw_classify() hit the WARN_ON() in [2]: WARNING: ./include/net/pkt_cls.h:88 at fw_classify+0x244/0x250 [cls_fw], CPU#18: mausezahn/1399 Modules linked in: cls_fw(E) act_skbedit(E) CPU: 18 UID: 0 PID: 1399 Comm: mausezahn Tainted: G E 7.0.0-rc6-virtme #17 PREEMPT(full) Tainted: [E]=UNSIGNED_MODULE Hardware name: Red Hat KVM, BIOS 1.16.3-2.el9 04/01/2014 RIP: 0010:fw_classify+0x244/0x250 [cls_fw] Code: 5c 49 c7 45 00 00 00 00 00 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 5b b8 ff ff ff ff 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 90 0b 90 eb a0 0f 1f 80 00 00 00 00 90 90 90 90 90 90 90 90 90 90 RSP: 0018:ffffd1b7026bf8a8 EFLAGS: 00010202 RAX: ffff8c5ac9c60800 RBX: ffff8c5ac99322c0 RCX: 0000000000000004 RDX: 0000000000000001 RSI: ffff8c5b74d7a000 RDI: ffff8c5ac8284f40 RBP: ffffd1b7026bf8d0 R08: 0000000000000000 R09: ffffd1b7026bf9b0 R10: 00000000ffffffff R11: 0000000000000000 R12: 0000000000010000 R13: ffffd1b7026bf930 R14: ffff8c5ac8284f40 R15: 0000000000000000 FS: 00007fca40c37740(0000) GS:fff
Code
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Timeline
Detection, updates, and resolution for this record.
Jun 24, 2026 · NIST NVD
Detected
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_fw: fix NULL dereference of "old" filters before change() Like pointed out by Sashiko [1], since commit ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") TC filters are added to a shared block and published to datapath before their ->change() function is called. This is a problem fo
Oct 15, 2026 · NIST NVD
Updated
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_fw: fix NULL dereference of "old" filters before change() Like pointed out by Sashiko [1], since commit ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") TC filters are added to a shared block and published to datapath before their ->change() function is called. This is a problem fo
Affected
- cpe linux/linux kernelversion unspecified
Sources
- CVE.orgVulnerability recordCVE-2026-53080
Official CVE identifier
cve.org - FIRST EPSSExploitation probabilityCVE-2026-53080
30-day exploitation probability 0.1%
first.org - NIST NVDVulnerability recordCVE-2026-53080
In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_fw: fix NULL dereference of "old" filters before change() Like pointed out by Sashiko [1], since commit ed76f5edccc9 ("net: sched: protect filter_chain list with filter_chain_lock mutex") TC filt
nvd.nist.gov